Radio terminal, radio communication system, and radio communication method

ABSTRACT

A radio terminal that performs radio communication with a base station, including: a communicator configured to perform radio measurement and monitoring of a paging signal; and a controller configured to control the communicator to receive information related to first duration by Non-Access Stratum (NAS) message from the base station, and not to perform the radio measurement and the monitoring during the first duration but to perform the radio measurement and the monitoring during second duration different from the first duration, wherein the controller is further configured to control the radio measurement and the monitoring by ending the first duration for transmitting uplink data of the radio terminal.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 16/419,626, filed May 22, 2019, which is a continuation applicationof U.S. application Ser. No. 15/013,434, filed Feb. 2, 2016, now U.S.Pat. No. 10,349,292, which is a continuation application of U.S.application Ser. No. 14/322,434, filed Jul. 2, 2014, now U.S. Pat. No.9,301,187, which is a continuation application of InternationalApplication PCT/JP2012/050540 filed on Jan. 13, 2012 which designatedthe U.S., the entire contents of which are incorporated herein byreference.

FIELD

The embodiments discussed herein relate to a radio terminal thatperforms radio communication, a radio communication system, and a radiocommunication method thereof.

BACKGROUND

The cellular mobile communication has evolved from the UMTS (UniversalMobile Telecommunication System) into the LTE (Long Term Evolution). Inthe LTE, the system based on the OFDM (Orthogonal Frequency DivisionMultiplexing) is specified as the radio access technology and high-speedradio packet communication with a downlink peak transmission rate of 100Mb/s or more and an uplink peak transmission rate of 50 Mb/s or more isenabled.

The 3GPP (3rd Generation Partnership Project), which is an internationalstandardization organization, has currently started examinations of theLTE-A (LTE-Advanced) based on the LTE toward realization of higher-speedcommunication. The LTE-A aims at a downlink peak transmission rate of 1Gb/s and an uplink peak transmission rate of 500 Mb/s and various newtechnologies, such as the radio access system and the networkarchitecture, are under study (for example, see 3GPP TR36.913 V9.0.0,3GPP TR36.912 V9.3.0, and 3GPP TS36.300 V10.4.0). On the other hand, theLTE-A is the system based on the LTE, and therefore, it is important tomaintain backward compatibility.

In the LTE or LTE-A, as the operation in the idle mode of a radioterminal, cell selection is specified. Specifically, cell selection andcell reselection are specified (for example, see 3GPP T536.304 V10.2.0and 3GPP T536.133 V10.3.0).

The cell selection is performed when the radio terminal turns on thepower and a PLMN (Public Land Mobile Network: mobile network operator)is selected. As the cell selection, cell selection (initial cellselection) performed by a radio terminal without knowing information ofa cell and cell selection (stored information cell selection) performedby a mobile station with knowledge of information of a cell arespecified.

In the cell selection, a radio terminal measures radio quality andselects a cell of good radio quality as a serving cell and camps on anetwork. More specifically, if the cell selection criteria “S”determined by RSRP (Reference Signal Received Power) and RSRQ (ReferenceSignal Received Quality) are satisfied, it is possible to camp on thecell (for example, see 3GPP TS36.304 V10.2.0). The radio terminal mayreceive an incoming call by camping on the network. The cell reselectionis performed in order to detect a cell of better radio quality and whenbetter radio quality is detected, the radio terminal camps on the cell.

Radio measurement in the idle mode is specified in order to detect acell of better radio quality (for example, see 3GPP TS36.133 V10.3.0).In the idle mode, it is needed to achieve a balance between powerconsumption of the radio terminal and accuracy of radio measurement.

For example, if the frequency of measurement is reduced in order tosuppress power consumption, the accuracy of measurement deteriorates andthere occurs a case where it is not possible to camp on an appropriatecell. On the other hand, if the frequency of measurement is increased inorder to improve the accuracy of measurement, power consumptionincreases. In view of this point, DRX (Discontinuous Reception) isspecified (for example, see 3GPP TS36.133 V10.3.0).

There are cases where a DRX cycle value of the DRX is acquired bybroadcast information broadcasted by the base station and where it isset by the NAS (Non Access Stratum), which is an upper layer. The radioterminal performs measurement at least once for each DRX and samples theradio quality. The radio terminal then averages the radio qualityaccording to sampling intervals specified by the function of the DRX andthen calculates a measured value of the radio quality.

Further, the radio terminal in the idle mode periodically monitors apaging signal in order to detect an incoming call. In the radioterminal, as in the case of the measurement described above, if thefrequency of monitoring of a paging signal is reduced, a communicationdelay occurs and if the frequency of monitoring of a paging signal isincreased, power consumption increases. Therefore, it is specified thatmonitoring of a paging signal is performed only once within the DRXcycle (for example, see 3GPP TS36.304 V10.2.0).

As described above, it is possible for the radio terminal to performcell selection and incoming call detection in consideration of powerconsumption by performing measurement and monitoring of a paging signalwithin the DRX cycle, which is the cycle of measurement.

It is specified that decision of whether or not to perform measurementand cell selection is performed at least once for each DRX cycle.Further, it is specified that sample values (specifically, values ofRSRP and RSRQ) of the radio quality obtained by measurement are filteredand averaged where the sample values are spaced by at least half of theDRX duration when calculating a measured value of measurement (forexample, see 3GPP TS36.133 V10.3.0).

Therefore, if the DRX cycle is increased in order to suppress powerconsumption of the radio terminal, the sampling interval of measurementincreases and there has been such a problem that the accuracy ofmeasurement deteriorates.

SUMMARY

According to an aspect of the embodiments, there is provide a radioterminal that performs radio communication with a base station,including: a communication unit configured to perform radio measurementand monitoring of a paging signal of the base station; and a controlunit configured to make it possible to control the communication unit soas to configure first duration and second duration, to receiveinformation of the first duration by Non-Access Stratum (NAS) messagefrom the base station, and to perform the radio measurement and themonitoring during the first duration but not to perform the radiomeasurement and the monitoring during the second duration following thefirst duration, wherein the control unit is further configured tocontrol the radio measurement and the monitoring by ending the secondduration for transmitting uplink data of the radio terminal to asuitable base station, the uplink data being originated during thesecond duration.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 explains a radio terminal according to a first embodiment;

FIG. 2 illustrates a radio communication system according to a secondembodiment;

FIG. 3 is a function block diagram of a radio terminal;

FIG. 4 illustrates a hardware configuration example of a radio terminal;

FIG. 5 is a function block diagram of a base station;

FIG. 6 illustrates a hardware configuration example of a base station;

FIG. 7 is part 1 of a timing chart of a radio terminal;

FIG. 8 is part 2 of the timing chart of the radio terminal;

FIG. 9 is a flowchart of a radio terminal;

FIG. 10 is a flowchart of a base station;

FIG. 11 is a timing chart of a radio terminal according to a thirdembodiment;

FIG. 12 explains a mask pattern of DRX;

FIG. 13 is a flowchart of a radio terminal;

FIG. 14 is a flowchart of a base station;

FIG. 15 is a timing chart of a radio terminal according to a fourthembodiment;

FIG. 16 is a flowchart of a radio terminal;

FIG. 17 is a flowchart of a base station;

FIG. 18 is a timing chart of a radio terminal according to a fifthembodiment;

FIG. 19 is a flowchart of a radio terminal;

FIG. 20 is a flowchart of a base station;

FIG. 21 is a timing chart of a radio terminal according to a sixthembodiment;

FIG. 22 explains operations of an NAS Attach procedure and an NAS Detachprocedure;

FIG. 23 is a flowchart of a radio terminal; and

FIG. 24 is a flowchart of a base station.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments are explained in detail with reference to thedrawings.

First Embodiment

FIG. 1 explains a radio terminal according to a first embodiment. Asillustrated in FIG. 1 , a radio terminal 1 has a communication unit 1 aand a controller 1 b. Arrows A1 to A3 illustrated in FIG. 1 indicatetiming of measurement of a base station, not illustrated, and timing ofmonitoring of a paging signal performed by the radio terminal 1. In FIG.1 , m indicates timing of measurement of a base station, notillustrated, and p indicates timing of monitoring of a paging signalperformed by the radio terminal 1.

The communication unit 1 a intermittently performs measurement of a basestation, not illustrated, and monitoring of a paging signal within theduration of a periodic duration T.

For example, T illustrated in FIG. 1 indicates DRX. The communicationunit 1 a intermittently performs measurement (m) of a base station andmonitoring of a paging signal (p) within a DRX cycle of the DRX.

The controller 1 b controls the communication unit 1 a so as to performmeasurement, within the duration T, with intervals intervals less thanhalf of the duration T. Further, it is also made possible to performfiltering of sample values (specifically, values of RSRP and RSRQ) ofradio quality obtained by measurement where the sample values are spacedby less than half of the duration T.

For example, as indicated by the arrow A1, the controller 1 b controlsthe communication unit 1 a so as to perform measurement where the samplevalues are spaced by less than half of the duration T. Specifically, thecontroller 1 b controls the communication unit 1 a so as to performmeasurement where the sample values are spaced by less than half of theDRX cycle.

The arrow A2 indicates an example of the conventional timing ofmeasurement and monitoring of a paging signal. As described previously,it is specified that decision of whether or not to perform measurementand cell selection is performed at least with intervals of the DRXcycle. Here, in order to suppress the power consumption of the radioterminal 1, the length (DRX cycle) of the duration T is increased asindicated by the arrow A3.

The arrow A3 indicates another example of the conventional timing ofmeasurement and monitoring of a paging signal. Without violating thespecification, measurement is performed with intervals of half the DRXcycle (DRX cycle/2). Further, in the calculation of measured values ofmeasurement, sample values of the measurement are averaged and theaveraged values are measurement result of the radio quality of eachcell. By performing measurement and calculation of measured values, itis possible to maintain the accuracy of measurement even if the length(DRX cycle) of the duration T increases. However, the conventionalinterval of measurement increases as the DRX cycle increases, andtherefore, the averaging interval of measurement increases and theaccuracy of measurement deteriorates.

In contrast to this, as described above, the controller 1 b controls thecommunication unit 1 a so as to perform measurement with intervals lessthan half of the length of the duration T. Further, also in thefiltering of sample values (specifically, values of RSRP and RSRQ) ofthe radio quality obtained by measurement, it is made possible toperform filtering where the sample values are spaced by less than halfof the length. Due to this, the radio terminal 1 may shorten theaveraging interval of measurement as well as suppressing powerconsumption, and may suppress deterioration in measurement.

As described above, the communication unit 1 a of the radio terminal 1performs measurement of the base station and monitoring of a pagingsignal within the duration of the periodic duration T. Then, thecontroller 1 b controls the communication unit 1 a so as to performmeasurement with intervals less than half of the length of the durationT within the duration T. Due to this, the radio terminal 1 may preventthe interval of measurement from increasing and may suppressdeterioration in measurement even if the length of the duration T isincreased in order to suppress power consumption.

Second Embodiment

Next, a second embodiment is explained in detail with reference todrawings.

FIG. 2 illustrates a radio communication system according to the secondembodiment. FIG. 2 illustrates a base station 11 and a radio terminal12. The base station 11 and the radio terminal 12 perform radiocommunication by the LTE-A or LTE communication system.

The radio terminal 12 is built in a device, such as a gas meter and anelectricity meter. The radio terminal 12 transmits information such asan anomaly and a usage fee detected by the device, for example, a gasmeter and an electricity meter, to the base station 11. The informationtransmitted to the base station 11 is transmitted to, for example, a gascompany or an electricity company.

The device as described above has communication characteristicsdifferent from those of a mobile telephone etc. For example, the devicedoes not move and the amount of communication is small. Consequently, itis thought that the device is in the idle mode in most of time andrarely enters the connected mode.

In the case where the device is installed in a condominium etc., thebase station 11 may be, for example, a home eNB (evolved Node B).Further, the device may be built in a sensor or a health meter formanaging human health condition, not limited to the above-describedmeter.

FIG. 3 is a function block diagram of a radio terminal. As illustratedin FIG. 3 , the radio terminal 12 has a communication unit 21 and acontroller 22. The controller 22 has a radio controller 22 a, a controlplane layer controller 22 b, and an application layer controller 22 c.

The communication unit 21 performs control of radio communication. Forexample, the communication unit 21 performs base band (BB) processingand radio frequency (RF) processing of a signal transmitted to andreceived from the base station 11. Further, the power of thecommunication unit 21 is turned on and off by the control of the radiocontroller 22 a of the controller 22.

The radio controller 22 a controls the BB processing and the RFprocessing of the communication unit 21. Further, the radio controller22 a performs turning on and off control of the power of thecommunication unit 21.

The control plane layer controller 22 b performs control of an RRC(Radio Resource Control) layer and an NAS layer.

The application layer controller 22 c performs control of an applicationlayer.

The communication unit 21 corresponds to, for example, the communicationunit 1 a in FIG. 1 . The radio controller 22 a and the control planelayer controller 22 b correspond to, for example, the controller 1 b inFIG. 1 .

FIG. 4 illustrates a hardware configuration example of a radio terminal.As illustrated in FIG. 4 , the radio terminal has a processor 31, a mainmemory 32, a ROM (Read Only Memory) 33, a storage 34, a communicationinterface 35, an input and output device 36, a display 37, and a bus 38.

To the processor 31, the maim memory 32, the ROM 33, the storage 34, thecommunication interface 35, the input and output device 36, and thedisplay 37 are connected via the bus 38. The whole of the radio terminal12 is controlled by the processor 31. The processor 31 is, for example,a CPU (Central Processing Unit) or a DSP (Digital Signal Processor).

In the main memory 32, data and programs used in various kinds ofprocessing of the processor 31 are temporarily stored. In the ROM 33,static information, such as a protocol to specify the operation of theradio terminal 12, is stored. For example, in the ROM 33, informationfor the processor 31 to perform data plane processing, control planeprocessing, scheduling processing, or the like is stored. In the storage34, data and programs used in various kinds of processing of theprocessor 31 are stored. The communication interface 35 performs radiocommunication with the base station 11. For example, the communicationinterface 35 converts a base band signal into a radio frequency andoutputs the radio frequency to an antenna, not illustrated. Further, thecommunication interface 35 frequency-converts a radio signal received byan antenna, not illustrated, into a base band signal.

The input and output device 36 is, for example, a key, a speaker, or amicrophone. For example, the key receives a character or a numeral inputby a user. The speaker, for example, converts a voice signal receivedfrom the base station 11 into voice and outputs the voice. Themicrophone converts voice of a user into an electric signal. The display37 is, for example, an LCD (Liquid Crystal Display). The display 37displays, for example, data received from the base station 11.

The function of the communication unit 21 in FIG. 3 is implemented by,for example, the communication interface 35. The function of thecontroller 22 is implemented by, for example, the processor 31.

FIG. 5 is a function block diagram of a base station. As illustrated inFIG. 5 , the base station 11 has a communication unit 41 and acontroller 42. The controller 42 has a radio controller 42 a and acontrol plane layer controller 42 b.

The communication unit 41 performs control of radio communication. Forexample, the communication unit 41 performs BB processing and RFprocessing of a signal transmitted to and received from the radioterminal 12.

The radio controller 42 a controls BB processing and RF processing ofthe communication unit 41.

The control plane layer controller 42 b performs control of the RRClayer and the NAS layer.

FIG. 6 illustrates a hardware configuration example of a base station.As illustrated in FIG. 6 , the base station 11 has a processor 51, amain memory 52, a ROM 53, a storage 54, a communication interface 55,and a bus 56.

To the processor 51, the main memory 52, the ROM 53, the storage 54, andthe communication interface 55 are connected via the bus 56. The wholeof the base station 11 is controlled by the processor 51. The processor51 is, for example, a CPU or a DSP.

In the main memory 52, data and programs used in various kinds ofprocessing of the processor 51 are temporarily stored. In the ROM 53,static information, such as a protocol to specify the operation of thebase station 11, is stored. For example, in the ROM 53, information forthe processor 51 to perform data plane processing, control planeprocessing, scheduling processing, or the like is stored. In the storage54, data and programs used in various kinds of processing of theprocessor 51 are stored. The communication interface 55 performs radiocommunication with the radio terminal 12. For example, the communicationinterface 55 converts a base band signal into a radio frequency andoutputs the radio frequency to an antenna, not illustrated. Further, thecommunication interface 55 frequency-converts a radio signal received byan antenna, not illustrated, into a base band signal. Furthermore, thecommunication interface 55 performs wired communication with ahigh-level apparatus, such as an S-GW (Serving-Gateway).

FIG. 7 is part 1 of a timing chart of a radio terminal. In FIG. 7 , mindicates timing of measurement of the radio terminal 12. Further, pindicates timing of monitoring of a paging signal of the radio terminal12.

In the example in FIG. 7 , the timings of m and p are different betweenbefore and after an event detected by the application layer. An eventoccurs by, for example, a charge report of an electricity meter or thelike and an anomaly report.

The radio terminal 12 uses a long DRX cycle longer than the normal DRXcycle in order to, for example, reduce power consumption.

Here, the measured value of the conventional measurement is calculatedby averaging samples of measurement having at least an interval of “DRXcycle/2”. Therefore, the interval of measurement increases, for example,as indicated by the arrow A3 in FIG. 1 and the measurement accuracy ofmeasurement deteriorates.

In contrast to this, in the radio terminal 12, measurement is performedat least once within the DRX duration as conventionally. Consequently,it is possible to perform measurement a plurality of times within theDRX duration. However, a measured value is calculated by filtering asample value of measurement wherein the sample values are spaced by‘long DRX cycle/n’ (n>2). Consequently, the radio terminal 12 performsmeasurement with intervals of ‘X’ illustrated in FIG. 7 .

The radio terminal 12 calculates a measured value of measurement by, forexample, averaging two measurements. For example, the radio terminal 12calculates a measured value using sample values of two measurements of mon the left side and of m on the right side in the long DRX cycle beforean event occurs illustrated in FIG. 7 . Further, the radio terminal 12calculates a measured value using sample values of measurements of thefirst m and the second m from the left in the long DRX cycle after theoccurrence of the event. Further, the radio terminal calculates ameasured value using sample values of measurements of the third m andthe fourth m from the left.

After the occurrence of the event, the number of times of measurementwithin the long DRX cycle has increased compared to that before theoccurrence of the event. For example, in FIG. 7 , before the occurrenceof the event, the number of times of measurement is two, but after theoccurrence of the event, the number of times is four. The reason forthis is that camping on an appropriate cell and appropriate notificationof event information to the base station are enabled by increasing thenumber of times of measurement to improve the accuracy of evaluation ofmeasurement. When determining that it is not possible to connect to theprevious cell by the measurement after the occurrence of the event, theradio terminal 12 performs cell selection to attempt detection of a newcell. Further, after transmitting UL data for the event, the radioterminal 12 returns to the operation before the occurrence of the event.

FIG. 8 is part 2 of the timing chart of the radio terminal. In thetiming chart in FIG. 8 , the interval of measurement after theoccurrence of an event is short, i.e., an interval Y, with respect tothe timing chart in FIG. 7 . In other words, in FIG. 8 , the frequencyof measurement is increased compared to that in FIG. 7 . Due to this,the power consumption of the radio terminal 12 increases compared tothat in FIG. 7 , but the accuracy of measurement improves because theinterval at which each sample is averaged is shortened in calculation ofa measured value of measurement.

However, this does not mean that the shorter the averaging interval, thebetter the measurement accuracy in calculation of a measured value ofmeasurement. If the averaging interval is too short, there is apossibility that an evaluation is made only in the instant of excellentradio propagation condition or conversely, a possibility that anevaluation is made only in the instant of poor radio propagationcondition. Therefore, it is recommended to set the interval between eachsample with keeping some interval. For example, in FIG. 7 , the intervalof filtering of measurement is set to ‘X/2’ and in FIG. 8 , the intervalof filtering of measurement is set to ‘Y/2’.

Note that, the radio terminal 12 may resume the usual measurementinterval after the occurrence of the event. For example, the radioterminal 12 may perform measurement with intervals of ‘DRX cycle/2’after the occurrence of the event.

Acquisition of n that determines the interval of measurement isexplained. For example, n is notified from the base station 11 bybroadcast information.

Specifically, after the power is turned on, the radio terminal 12 makesan initial cell search and camps on a cell of good radio quality(suitable cell). At this time, the radio terminal 12 performs an NASAttach procedure. When camping on a cell, the radio terminal 12 acquiresthe broadcast information of the cell from the base station 11 andacquires n from the acquired broadcast information. Due to this, theradio terminal 12 may calculate the interval of measurement.

As illustrated in FIG. 8 , when the interval of measurement is changedbetween before and after the occurrence of the event, the radio terminal12 may notify the base station 11 that an event has occurred and thebase station 11 may notify the radio terminal 12 of new n. The basestation 11 may also change n in accordance with, for example, the typeof the event (e.g., whether or not the event is an emergency event).

Further, n may be determined in advance or may be calculated from thedevice ID. For example, the device ID is indicated by a value of 12bits. The radio terminal 12 may divide the device ID of the radioterminal 12 by, for example, an appropriate value, such as 4,000, andmay set the remainder to n.

The base station 11 may also notify the radio terminal of the number oftimes of measurement within the long DRX cycle by broadcast information.Further, the base station 11 may notify the number of times ofmeasurement within the long DRX cycle when receiving event notificationfrom the radio terminal 12.

FIG. 9 is a flowchart of a radio terminal.

(Step S1) The power of the radio terminal 12 is turned on.

(Step S2) The control plane layer controller 22 b receives broadcastinformation from the base station 11. In other words, the control planelayer controller 22 b receives ‘n’ which is used to calculate theinterval of measurement.

(Step S3) The control plane layer controller 22 b performs the NASAttach procedure.

(Step S4) The control plane layer controller 22 b calculates theinterval of measurement from the received ‘n’. The radio controller 22 aturns on and off the communication unit 21 so as to perform measurementwith intervals calculated by the control plane layer controller 22 b.The control plane layer controller 22 b averages the measuredmeasurements to evaluate the quality thereof.

The control plane layer controller 22 b performs monitoring of pagingwith, for example, timing that satisfies the following expression.SFN mod T=(T div N)*(UE-ID mod N)

SFN is a system frame number. T is a DRX cycle (long DRX cycle). UE-IDis an ID of the radio terminal. N is a value determined by the DRXcycle.

(Step S5) The application layer controller 22 c stands by for an event.

(Step S6) The application layer controller 22 c determines whether ornot an event has occurred. In the case where an event has occurred, theapplication layer controller 22 c proceeds to step S7. In the case whereno event has occurred, the application layer controller 22 c proceeds tostep S5.

(Step S7) The control plane layer controller 22 b and the radiocontroller 22 a perform measurement with new settings and make anevaluation of the quality thereof. For example, the control plane layercontroller 22 b performs measurement with new settings as explained inFIG. 8 . The control plane layer controller 22 b may perform measurementas illustrated in FIG. 7 .

FIG. 10 is a flowchart of a base station.

(Step S11) The control plane layer controller 42 b notifies the radioterminal 12 of broadcast information via the radio controller 42 a. Thebroadcast information includes ‘n’ which is used to calculate theinterval of measurement.

(Step S12) The control plane layer controller 42 b performs the NASAttach procedure.

(Step S13) The control plane layer controller 42 b stands by for anevent report from the radio terminal 12.

(Step S14) The control plane layer controller 42 b determines whether ornot the event report from the radio terminal 12 is received. In the casewhere the event report from the radio terminal 12 is received, thecontrol plane layer controller 42 b proceeds to step S15. In the casewhere the event report from the radio terminal 12 is not received, thecontrol plane layer controller 42 b proceeds to step S13.

(Step S15) The control plane layer controller 42 b notifies the radioterminal 12 of new ‘n’.

As described above, the control plane layer controller 22 b and theradio controller 22 a control the communication unit so as to performfiltering of measurement, within the long DRX cycle, with intervals lessthan half of the length of the long DRX cycle. Due to this, the radioterminal 12 may suppress an increase in the interval of measurement andmay suppress deterioration in the accuracy of measurement even if thelong DRX cycle is adopted in order to suppress power consumption.

Further, the control plane layer controller 22 b and the radiocontroller 22 a, after the occurrence of the event, increase the numberof times of measurement within the long DRX cycle compared to thatbefore the event. Due to this, the radio terminal 12 may improve thequality of measurement.

Further, the control plane layer controller 22 b and the radiocontroller 22 a, after the occurrence of the event, reduce the intervalof measurement compared to that before the event. Due to this, the radioterminal 12 may improve the quality of measurement

Third Embodiment

Next, a third embodiment is explained in detail with reference todrawings. In the third embodiment, masking is performed on theconventional DRX to provide a duration in which the DRX is not performedand the DRX is performed periodically. Although the conventional DRX maybe performed in the duration in which the DRX is performed, in order toimprove the quality of measurement, it may also be possible to performmeasurement a plurality of times within the DRX cycle and to performfiltering of measurement with intervals less than half of the length ofthe DRX cycle.

Note that, the radio communication system according to the thirdembodiment is the same as that in FIG. 2 . The block of the radioterminal 12 is the same as that in FIG. 3 , but the function of thecontrol plane layer controller 22 b is different. The hardwareconfiguration of the radio terminal 12 is the same as that in FIG. 4 .The block of the base station 11 is the same as that in FIG. 5 , but thefunction of the control plane layer controller 42 b is different. Thehardware configuration of the base station 11 is the same as that inFIG. 6 .

FIG. 11 is a timing chart of a radio terminal according to the thirdembodiment. In FIG. 11 , the long DRX cycle in FIG. 7 is replaced withthe DRX cycle. Other portions in FIG. 11 are the same as those in FIG. 7, and therefore, explanation thereof is omitted.

The radio terminal 12 acts so that, before an event occurs, the DRXcycle is masked in which measurement is not performed and the DRX isperformed periodically (thick line in FIG. 11 ). The radio terminal 12performs measurement and monitoring of a paging signal within the DRXcycle not masked.

In the section not masked, the radio terminal 12 performs measurement atintervals of ‘DRX cycle/n’ (n>2) as illustrated in FIG. 11 .Consequently, the radio terminal 12 performs filtering of measurement atintervals of ‘X’ illustrated in FIG. 11 .

After the occurrence of the event, the radio terminal does not mask theDRX cycle. In other words, the radio terminal 12 performs measurementand monitoring of a paging signal in each DRX cycle as illustrated inFIG. 11 .

FIG. 12 explains a mask pattern of the DRX. The control plane layercontroller 22 b of the radio terminal 12 releases the mask of the DRX insynchronization with the BCCH (Broadcasting Control Channel)modification period, which is the period to check a change of thebroadcast information.

Double-headed arrows A11, A12 illustrated in FIG. 12 indicate the BCCHmodification period. The control plane layer controller 22 b releasesthe mask of the DRX with timing of dotted lines A13, A14 illustrated inFIG. 12 . For example, the control plane layer controller 22 b controlsthe radio controller 22 a so as to turn on the communication unit 21 (soas to perform DRX) with the timing of the dotted lines A13, A14.

The alternate long and short dash line illustrated in FIG. 12 indicatesthe period of time during which the mask of the DRX cycle is released(period of time during which DRX is performed). The rectangle and therectangle with slashes illustrated in FIG. 12 indicate the broadcastinformation (SIB: System Information Block) notified to the radioterminal 12 from the base station 11.

The control plane layer controller 22 b monitors SIB1 (rectangle withslashes rising toward the right in FIG. 12 ) or a paging signal to checkwhether or not there is a change in the broadcast information. Thecontrol plane layer controller 22 b turns on the communication unit 21to monitor the SIB1 and paging signal. The control plane layercontroller 22 b performs measurement and monitoring of a paging signalby utilizing this timing. The rectangle with slashes falling toward theright indicates the SIB whose information has been changed.

The period of time during which the mask is released may be notified by,for example, broadcast information, or may be determined in advance.Further, the period of time may be calculated from the device ID of theradio terminal 12. Furthermore, the radio terminal 12 may freely releasethe mask by implementation thereof.

In the above, it is described that the mask pattern synchronizes withthe BCCH modification period, and now a setting example of another maskpattern is explained.

Example 1: The base station 11 broadcasts a masking pattern by broadcastinformation. For example, the base station broadcasts within which DRXcycle to perform the DRX by broadcast information. The control planelayer controller 22 b of the radio terminal 12 releases the mask withinthe DRX cycle included in the received broadcast information andperforms measurement and monitoring of a paging signal. The period oftime during which the mask is released may be broadcasted by, forexample, broadcast information, or may be determined in advance.Further, the period of time may be calculated from the device ID of theradio terminal 12.

Example 2: A masking pattern is notified by a paging signal. Forexample, when the radio terminal 12 camps on, the base station 11notifies a masking pattern of the DRX by a paging signal.

Example 3: When the radio terminal 12 camps on, the location isregistered in an MME (Mobility Management Entity). The locationregistration is performed in the NAS layer and the NAS Attach procedureis performed. The radio terminal 12 receives a masking pattern by an NASAttach Accept of an NAS message transmitted and received by the NASAttach procedure.

Example 4: Each time the DRX is masked N times, the masking of the DRXis released. N may be notified by broadcast information from the basestation 11 or may be determined in advance by the base station 11 andthe radio terminal 12. Further, N may be calculated from the device IDof the radio terminal 12.

Example 5: Based on an IMSI (International Mobile Subscriber Identity),which is an identifier of a radio terminal, a radio frame in which themask of the DRX is released is determined. For example, the mask of theDRX is released in the radio frame in which the SFN mod DRX cycle andfunc (IMSI) become equal to each other. The func ( ) is an appropriatefunction and for example, a function that outputs a value by the IMSI.

FIG. 13 is a flowchart of a radio terminal.

(Step S21) The power of the radio terminal 12 is turned on.

(Step S22) The control plane layer controller 22 b receives broadcastinformation from the base station 11.

(Step S23) The control plane layer controller 22 b performs the NASAttach procedure.

(Step S24) The control plane layer controller 22 b receives a maskpattern of the DRX by performing the NAS Attach procedure. The flowchartin FIG. 13 illustrates a processing example in the case of Example 3described above.

(Step S25) The control plane layer controller 22 b controls the radiocontroller 22 a so as to perform the DRX with the received mask pattern.The radio controller 22 a turns on and off the communication unit 21 inaccordance with the control of the control plane layer controller 22 bso that measurement and monitoring of a paging signal are performed. Thecontrol plane layer controller 22 b averages measured measurements toevaluate the quality thereof.

(Step S26) The application layer controller 22 c stands by for an event.

(Step S27) The application layer controller 22 c determines whether ornot the event has occurred. In the case where the event has occurred,the application layer controller 22 c proceeds to step S28. In the casewhere no event has occurred, the application layer controller 22 cproceeds to step S26.

(Step S28) The control plane layer controller 22 b releases all themasks. For example, the control plane layer controller 22 b controls theradio controller 22 a so that measurement and monitoring of a pagingsignal are performed in each DRX cycle as illustrated after theoccurrence of the event in FIG. 11 .

FIG. 14 is a flowchart of a base station.

(Step S31) The control plane layer controller 42 b notifies the radioterminal 12 of broadcast information via the radio controller 42 a.

(Step S32) The control plane layer controller 42 b performs the NASAttach procedure.

(Step S33) The control plane layer controller 42 b transmits a maskpattern of the DRX by the NAS Attach procedure. The flowchart in FIG. 14illustrates a processing example in the case of Example 3 describedabove.

(Step S34) The control plane layer controller 42 b stands by for anevent report from the radio terminal 12.

(Step S35) The control plane layer controller 42 b determines whether ornot the event report from the radio terminal 12 is received. In the casewhere the event report from the radio terminal 12 is received, thecontrol plane layer controller 42 b ends the processing. In the casewhere the event report from the radio terminal 12 is not received, thecontrol plane layer controller 42 b proceeds to step S34.

As described above, the control plane layer controller 42 b acts so thata duration during which the DRX is not performed is set and the DRX isperformed periodically. Then, the control plane layer controller 42 band the radio controller 42 a perform filtering of measurement atintervals less than half the cycle length of the DRX cycle within theDRX cycle of the DRX performed periodically. Due to this, the radioterminal 12 may suppress an increase in the interval of measurement andmay suppress deterioration in measurement within the DRX cycle of theDRX performed periodically in order to suppress power consumption.

Fourth Embodiment

Next, a fourth embodiment is explained in detail with reference todrawings. In the fourth embodiment, the base station specifies the DRXto be performed next.

The radio communication system according to the fourth embodiment is thesame as that in FIG. 2 . The block of the radio terminal 12 is the sameas that in FIG. 3 , but the function of the control plane layercontroller 22 b is different. The hardware configuration of the radioterminal 12 is the same as that in FIG. 4 . The block of the basestation 11 is the same as that in FIG. 5 , but the function of thecontrol plane layer controller 42 b is different. The hardwareconfiguration of the base station 11 is the same as that in FIG. 6 .

FIG. 15 is a timing chart of a radio terminal according to the fourthembodiment. In FIG. 15 , the DRX to be performed next is specified by apaging signal, which is different from FIG. 11 . Other portions in FIG.15 are the same as those in FIG. 11 , and therefore, explanation thereofis omitted.

When camping on a cell of the base station 11, the control plane layercontroller 22 b of the radio terminal 12 performs measurement andmonitoring of a paging signal. The base station 11 specifies withinwhich DRX the radio terminal 12 next performs measurement and monitoringof a paging signal by a paging signal. The control plane layercontroller 22 b performs measurement and monitoring of a paging signalwithin the specified DRX.

The period of time during which the DRX is performed may be specified bythe paging signal or notified by broadcast information. Further, theperiod of time may be determined in advance or may be calculated fromthe device ID of the radio terminal 12. Furthermore, the period of timemay be determined by implementation of the radio terminal. For example,the base station 11 specifies the start of the DRX by broadcastinformation and the period of time of the DRX is determined byimplementation of the radio terminal 12.

The base station 11 may specify to perform the DRX by the NAS. Forexample, when the radio terminal 12 camps on, the location is registeredin the MME. The location registration is performed in the NAS layer andthe NAS Attach procedure is performed. The base station 11 specifies theDRX to be performed next by the NAS Attach Accept of the NAS messagetransmitted and received by the NAS Attach procedure. The period of timeduring which the DRX is performed may be notified by the NAS AttachAccept or notified by broadcast information. Further, the period of timemay be determined in advance or may be determined by the device ID ofthe radio terminal 12.

FIG. 16 is a flowchart of a radio terminal.

(Step S41) The power of the radio terminal 12 is turned on.

(Step S42) The control plane layer controller 22 b receives broadcastinformation from the base station 11.

(Step S43) The control plane layer controller 22 b performs the NASAttach procedure.

(Step S44) The control plane layer controller 22 b receives the DRX tobe performed next by a paging signal or by performing the NAS Attachprocedure.

(Step S45) The control plane layer controller 22 b controls the radiocontroller 22 a so as to perform the DRX specified by the base station11 (step S44). The control plane layer controller 22 b performsmeasurement by the DRX and makes an evaluation thereof.

(Step S46) The application layer controller 22 c stands by for an event.

(Step S47) The application layer controller 22 c determines whether ornot the event has occurred. In the case where the event has occurred,the application layer controller 22 c proceeds to step S48. In the casewhere no event has occurred, the application layer controller 22 cproceeds to step S46.

(Step S48) The control plane layer controller 22 b performs all theDRXs. For example, as illustrated after the occurrence of the event inFIG. 15 , the control plane layer controller 22 b controls the radiocontroller 22 a so that measurement and monitoring of a paging signalare performed in each DRX cycle.

FIG. 17 is a flowchart of a base station.

(Step S51) The control plane layer controller 42 b notifies the radioterminal 12 of broadcast information via the radio controller 42 a.

(Step S52) The control plane layer controller 42 b performs the NASAttach procedure.

(Step S53) The control plane layer controller 42 b transmits the DRX tobe performed next by a paging signal or by performing the NAS Attachprocedure.

(Step S54) The control plane layer controller 42 b stands by for anevent report from the radio terminal 12.

(Step S55) The control plane layer controller 42 b determines whether ornot to have received an event report from the radio terminal 12. In thecase of having received an event report from the radio terminal 12, thecontrol plane layer controller 42 b ends the processing. In the case ofnot having received an event report from the radio terminal 12, thecontrol plane layer controller 42 b proceeds to step S54.

As described above, the control plane layer controller 42 b receives theDRX to be performed next by a paging signal or the NAS. Then, thecontrol plane layer controller 42 b and the radio controller 42 aperform filtering of measurement at intervals less than half the cyclelength of the DRX cycle within the DRX cycle of the DRX to be performednext. Due to this, the radio terminal 12 may suppress deterioration inmeasurement as well as suppressing power consumption.

Fifth Embodiment

Next, a fifth embodiment is explained in detail with reference todrawings. In the fifth embodiment, two DRX cycles are set andmeasurement and monitoring of a paging signal are performed.

The radio communication system according to the fifth embodiment is thesame as that in FIG. 2 . The block of the radio terminal 12 is the sameas that in FIG. 3 , but the function of the control plane layercontroller 22 b is different. The hardware configuration of the radioterminal 12 is the same as that in FIG. 4 . The block of the basestation 11 is the same as that in FIG. 5 , but the function of thecontrol plane layer controller 42 b is different. The hardwareconfiguration of the base station 11 is the same as that in FIG. 6 .

FIG. 18 is a timing chart of a radio terminal according to the fifthembodiment. FIG. 18 illustrates a short DRX cycle and a long DRX cyclewhose period of time is longer than that of the short DRX cycle. Theshort DRX cycle is, for example, the conventional DRX cycle and the longDRX cycle is made longer in cycle than the short DRX cycle in order tosuppress power consumption of the radio terminal 12.

The radio terminal 12 performs the DRX in the short DRX cycle, forexample, for a predetermined period of time and after that, performs theDRX in the long DRX cycle for a predetermined period of time. Then, theradio terminal 12 repeats these operations. The period of time duringwhich the DRX in the short DRX cycle is performed and the period of timeduring which the DRX in the long DRX cycle is performed are notified bybroadcast information, for example.

If the DRX cycle is lengthened simply, the interval of time during whichmeasurement is performed is also lengthened, and therefore, the controlplane layer controller 22 b of the radio terminal 12 performsmeasurement, within the long DRX, at least once with conventionalintervals of the DRX. Consequently, it is possible to performmeasurement a plurality of times within a DRX duration. However,measurement is performed with intervals of ‘long DRX cycle/n’ (n>2).Consequently, the radio terminal 12 performs control so as to performfiltering of measurement at least with an interval of ‘X’ as illustratedin FIG. 18 . The control plane layer controller 22 b may performmeasurement as conventionally in the short DRX cycle, but in order toimprove measurement accuracy, performs filtering of measurement at leastwith an interval of ‘short DRX cycle/2’.

The radio terminal 12 averages two measurements to calculate a measuredvalue of measurement. For example, the radio terminal 12 performsfiltering of two sample values of m on the left side and of m on theright side in the long DRX cycle illustrated in FIG. 18 .

As a modification example, if the DRX cycle is lengthened simply, it isobvious that the interval of time during which measurement is performedis lengthened, and therefore, there is also a method in whichmeasurement and monitoring of a paging signal are not at all performedin the long DRX cycle.

In the above, the period of time during which the DRX in the short DRXcycle is performed and the period of time during which the DRX in thelong DRX cycle is performed are notified by broadcast information, andhere, another example is explained.

Example 1: When the radio terminal 12 camps on, the base station 11notifies a period of time during which the DRX is performed by a pagingsignal.

Example 2: When the radio terminal 12 camps on, the location isregistered in the MME. The location registration is performed in the NASlayer and the NAS Attach procedure is performed. The radio terminal 12receives a period of time during which the DRX is performed by the NASAttach Accept of the NAS message transmitted and received by the NASAttach procedure.

Example 3: The control plane layer controller 22 b performs the DRX inthe short DRX cycle N times, and then, performs the DRX in the long DRXcycle M times. The values of N and M may be notified by broadcastinformation or values determined in advance may be used. Further, thecontrol plane layer controller 22 b may calculate the values of N and Mfrom the device ID of the radio terminal 12.

Example 4: The control plane layer controller 22 b switches the DRXcycles in conjunction with the BCCH modification period explained inFIG. 12 . For example, the control plane layer controller 22 b performsthe DRX in the short DRX cycle every N modification boundaries (thedotted lines A13, A14 in FIG. 12 ). The period of time during which theDRX in the short DRX cycle is performed may be notified by, for example,broadcast information or a value determined in advance may be used.Further, the control plane layer controller 22 b may calculate a periodof time during which the DRX in the short DRX cycle is performed fromthe device ID of the radio terminal 12.

Example 5: The control plane layer controller 22 b starts the DRX in theshort DRX cycle in the radio frame in which the SFN mod DRX cycle andthe func (IMSI) become equal to each other. The control plane layercontroller 22 b performs the DRX in the short DRX cycle in N successiveradio frames. N may be notified by, for example, broadcast informationor a value determined in advance may be used. Further, the control planelayer controller 22 b may calculate N from the device ID of the radioterminal 12. When ending the DRX in the short DRX cycle, the controlplane layer controller 22 b performs the DRX in the long DRX cycle.

FIG. 19 is a flowchart of a radio terminal.

(Step S61) The power of the radio terminal 12 is turned on.

(Step S62) The control plane layer controller 22 b receives broadcastinformation from the base station 11.

(Step S63) The control plane layer controller 22 b performs the NASAttach procedure.

(Step S64) The control plane layer controller 22 b acquires a period oftime during which the DRX in the short DRX cycle is performed and aperiod of time during which the DRX in the long DRX cycle is performedby the NAS Attach Accept, for example. The control plane layercontroller 22 b may also acquire a period of time during which the DRXin the short DRX cycle is performed and a period of time during whichthe DRX in the long DRX cycle is performed from broadcast information.

(Step S65) The control plane layer controller 22 b controls the radiocontroller 22 a so as to perform the DRX in the short DRX cycle and inthe long DRX cycle specified by the base station 11 (step S64). Thecontrol plane layer controller 22 b performs measurement by the DRX andmakes an evaluation thereof.

FIG. 20 is a flowchart of a base station.

(Step S71) The control plane layer controller 42 b notifies the radioterminal 12 of broadcast information via the radio controller 42 a.

(Step S72) The control plane layer controller 42 b performs the NASAttach procedure.

(Step S73) The control plane layer controller 42 b transmits the periodof time during which the DRX in the short DRX cycle and the DRX in thelong DRX cycle are performed by broadcast information or by performingthe NAS Attach procedure, for example.

As described above, the control plane layer controller 42 b performs theDRX in the short DRX cycle and in the long DRX cycle. Due to this, theradio terminal 12 may improve accuracy of measurement by the short DRXcycle as well as suppressing power consumption by the long DRX cycle.

Sixth Embodiment

Next, a sixth embodiment is explained in detail with reference todrawings. In the sixth embodiment, after the power of the radio terminal12 is turned on, the NAS Attach procedure and the NAS Detach procedureare performed. After that, the radio terminal 12 turns off the power ofthe communication unit 21. After that, if an event is detected in theapplication layer, the radio terminal 12 performs measurement andmonitoring of a paging signal by the DRX and for example, transmitsinformation of the event to the base station 11 by the UL.

The radio communication system according to the six embodiment is thesame as that in FIG. 2 . The block of the radio terminal 12 is the sameas that in FIG. 3 , but the function of the control plane layercontroller 22 b is different. The hardware configuration of the radioterminal 12 is the same as that in FIG. 4 . The block of the basestation 11 is the same as that in FIG. 5 , but the function of thecontrol plane layer controller 42 b is different. The hardwareconfiguration of the base station 11 is the same as that in FIG. 6 .

FIG. 21 is a timing chart of a radio terminal according to the sixthembodiment. An arrow A21 in FIG. 21 indicates performing of the NASAttach procedure and an arrow A22 indicates performing of the NAS Detachprocedure. When the power is turned on, the radio terminal 12 makes acell search and registers the location by performing the NAS Attachprocedure as indicated by the arrow A21. Then, the radio terminal 12turns off the power of the communication unit 21 by performing the NASDetach procedure as indicated by the arrow A22.

When detecting an event having occurred in the application layer, theapplication layer controller 22 c of the radio terminal 12 notifies thecontrol plane layer controller 22 b of the detection. The control planelayer controller 22 b controls the radio controller 22 a so as to turnon the communication unit 21.

The control plane layer controller 22 b registers the location byperforming the NAS Attach procedure as indicated by an arrow A23. Thecontrol plane layer controller 22 b performs the DRX in the short DRXcycle to perform measurement and monitoring of a paging signal.

The control plane layer controller 22 b transmits event information tothe base station 11 as UL data and performs the NAS Detach procedure asindicated by an arrow A24. Then, the control plane layer controller 22 bturns off the power of the communication unit 21.

After that, when an event is detected by the application layercontroller 22 c, the control plane layer controller 22 b performs thesame operation as that described above.

FIG. 22 explains the operations of the NAS Attach procedure and the NASDetach procedure.

(Step S81) The control plane layer controller 22 b of the radio terminal12 transmits an NAS Attach Request to the base station 11.

(Step S82) The control plane layer controller 42 b of the base station11 transmits the NAS Attach Accept to the radio terminal 12.

(Step S83) The control plane layer controller 22 b of the radio terminal12 transmits an NAS Attach Complete to the base station 11.

(Step S84) The control plane layer controller 22 b of the radio terminal12 transmits an NAS Detach Request to the base station 11.

(Step S85) The control plane layer controller 42 b of the base station11 transmits the NAS Detach Accept to the radio terminal 12.

FIG. 23 is a flowchart of a radio terminal.

(Step S91) The power of the radio terminal 12 is turned on.

(Step S92) The control plane layer controller 22 b performs the NASAttach procedure and the NAS Detach procedure. For example, the controlplane layer controller 22 b performs what is indicated by the arrow A21and what is indicated by the arrow A22 illustrated in FIG. 21 .

(Step S93) The application layer controller 22 c stands by for an event.

(Step S94) The application layer controller 22 c determines whether ornot an event has occurred. In the case where an event has occurred, theapplication layer controller 22 c proceeds to step S95. In the casewhere no event has occurred, the application layer controller 22 cproceeds to step S93.

(Step S95) The radio controller 22 a turns on the communication unit 21in accordance with the control of the control plane layer controller 22b.

(Step S96) The control plane layer controller 22 b causes the DRX to beperformed.

(Step S97) The control plane layer controller 22 b performs the NASAttach procedure.

(Step S98) The communication unit 21 transmits event information in theUL to the base station 11.

(Step S99) The control plane layer controller 22 b performs the NASDetach procedure.

FIG. 24 is a flowchart of a base station.

(Step S101) The control plane layer controller 42 b performs the NASAttach procedure.

(Step S102) The control plane layer controller 42 b communicates withthe radio terminal 12 via the radio controller 42 a and thecommunication unit 41.

(Step S103) The control plane layer controller 42 b performs the NASDetach procedure. The above-described processing is the same before andafter the event.

As described above, the control plane layer controller 42 b controls theradio controller 22 a so as to perform the DRX in conjunction with eventdetection by the application layer controller 22 c. Due to this, theradio terminal 12 may suppress power consumption before an event occurs.

According to the disclosed apparatus and method, it is possible tosuppress deterioration in measurement.

All examples and conditional language provided herein are intended forthe pedagogical purposes of aiding the reader in understanding theinvention and the concepts contributed by the inventor to further theart, and are not to be construed as limitations to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although one or more embodiments of thepresent invention have been described in detail, it should be understoodthat various changes, substitutions, and alterations could be madehereto without departing from the spirit and scope of the invention.

What is claimed is:
 1. A radio terminal that performs radiocommunication with a base station, comprising: a communicator configuredto perform radio measurement and monitoring of a paging signal of thebase station; and a controller configured to: control the communicatorto receive information related to first duration, the information beingtransmitted from the base station via a first Non-Access Stratum (NAS)message, control the communicator to not perform the radio measurementand the monitoring during the first duration, and control thecommunicator to perform repeatedly, according to a predetermined rule,the radio measurement and the monitoring during second duration which isdifferent from the first duration, the predetermined rule relating to aDiscontinuous Reception (DRX) cycle in the second duration, wherein thecontroller is further configured to receive a message which is differentfrom the first Non-Access Stratum message from the base station andcontrol the radio measurement and the monitoring during the secondduration according to the information.
 2. The radio terminal accordingto claim 1, wherein the message is a second Non-Access Stratum messageand the second Non-Access Stratum message is different from the firstNon-Access Stratum message.
 3. The radio terminal according to claim 1,wherein the information related to the first duration is informationrelating to length of the first duration.
 4. The radio terminalaccording to claim 1, wherein the first Non-Access Stratum message is anaccept message in response to a request message of NAS layer.
 5. Theradio terminal according to claim 1, wherein the message is the pagingsignal.
 6. A radio communication system comprising of a radio terminaland a base station that performs radio communication with the radioterminal, the radio terminal comprising: a communicator configured toperform radio measurement and monitoring of a paging signal of the basestation; and a controller configured to: control the communicator toreceive information related to first duration, the information beingtransmitted from the base station via a first Non-Access Stratum (NAS)message, control the communicator to not perform the radio measurementand the monitoring during the first duration, and control thecommunicator to perform repeatedly, according to a predetermined rule,the radio measurement and the monitoring during second duration which isdifferent from the first duration, the predetermined rule relating to aDiscontinuous Reception (DRX) cycle in the second duration, wherein thecontroller is further configured to receive a message which is differentfrom the first Non-Access Stratum message from the base station andcontrol the radio measurement and the monitoring during the secondduration according to the information.
 7. A base station that performsradio communication with a radio terminal, the base station comprising:a communicator configured to transmit information related to firstduration to be set in the radio terminal, the information beingtransmitted via a Non-Access Stratum (NAS) message to the radioterminal, the first duration being duration in which the radio terminaldoes not perform radio measurement and monitoring of a paging signal ofthe base station, and second duration which is different from the firstduration is a duration in which the radio terminal performs repeatedlythe radio measurement and the monitoring according to a predeterminedrule relating to a Discontinuous Reception (DRX) cycle in the secondduration, wherein the communicator is further configured to send amessage which is different from the Non-Access Stratum message and theradio terminal that receives the message controls the radio measurementand the monitoring during the second duration.
 8. A radio communicationmethod for a radio terminal and a base station that performs radiocommunication with the radio terminal, the radio communication methodcomprising: by the radio terminal, performing radio measurement andmonitoring of a paging signal of the base station; controllingcommunication to receive information related to first duration, theinformation being transmitted from the base station via a firstNon-Access Stratum (NAS) message, controlling the communication to notperform the radio measurement and the monitoring during the firstduration, and controlling the communication to perform repeatedly,according to a predetermined rule, the radio measurement and themonitoring during second duration which is different from the firstduration, the predetermined rule relating to a Discontinuous Reception(DRX) cycle in the second duration, wherein the radio terminal isconfigured to receive a message which is different from the firstNon-Access Stratum message from the base station and control the radiomeasurement and the monitoring during the second duration according tothe information.